For example, in a liquid crystal display device of an active matrix type, substrates are disposed so as to be opposed via liquid crystal, and gate signal lines extending in an x direction are disposed in parallel in a y direction and source signal lines extending in the y direction are disposed in parallel in the x direction on a surface of one of the substrates on a liquid crystal side. Further, a region surrounded by the gate signal lines and the source signal lines corresponds to a pixel region, and the pixel region includes at least a thin film transistor to be turned on by a signal (scanning signal) from the gate signal line and a pixel electrode to which a video signal from the source signal line is supplied via the turned-on thin film transistor.
The thin film transistor, the gate signal line, the source signal line, the pixel electrode and others are formed by stacking a conductive layer, a semiconductor layer, an insulating film and others processed into desired patterns by a selective etching by a photolithography technique on a substrate in a desired sequence.
In the display device thus configured, the reduction in the number of steps for the selective etching by the photolithography technique has been required, and for example, a technique has been known, in which conductive properties are given to predetermined regions of a semiconductor material film formed on a substrate, thereby processing the film into a channel region portion, a source region portion, and a drain region portion of the thin film transistor, and at the same time, forming a pixel electrode connected to the drain region portion (Japanese Patent Application Laid-Open Publication No. 2003-050405 (Patent Document 1)).